1. Technical Field
The present disclosure relates to a light-emitting device, and in particular to a light-emitting device comprising a first light-emitting unit, a second light-emitting unit, and a first switching unit, wherein the electrical connection between the first and second light-emitting units is controlled by the first switching unit.
2. Description of the Related Art
The light-emitting diodes (LEDs) of the solid-state lighting elements have the characteristics of the low power consumption, low heat generation, long operational life, shockproof, small volume, quick response and good opto-electrical property like light emission with a stable wavelength, so the LEDs have been widely used in household appliances, indicator light of instruments, and opto-electrical products, etc.
The conventional LED is driven by direct current (DC). An AC-DC converter is required to convert DC to AC. Since the converter has a large volume and heavy weight, the cost is added and the power is lost during converting. It is difficult for LED to compete with the existing light source mainly because of the price concern.
Alternating current light-emitting diodes (ACLED) have been developed to resolve the aforesaid problems and have advantages in small volume, lightweight, and low cost. In addition, 15%-30% electrical power loss produced by converting alternating current to direct current is reduced in the conventional LED, thereby improving the total efficiency of LEDs.
However, an operating voltage of the above-described ACLED is relatively high. Therefore, ACLED is not operated at most ranges of the alternating supply voltage.